Distillation and reflux are common chemical laboratory processes to prepare a substance for analysis or a subsequent chemical process.
The distillation process includes the steps of turning a substance in a liquid matrix into a vapor, cooling the vapor to condense it and collecting the resulting condensed liquid in order to separate the analyte of interest from its original matrix. Distillations are often carried out under specific temperatures to allow separation of compounds by their boiling point differences. Two common variations on the basic distillation process are often used. The first variation includes introducing an inert gas such as nitrogen or helium into the distillation apparatus to avoid atmospheric contamination or reacting the distilled compounds with atmospheric components during distillation. A second variation includes generating a gas from a heated liquid and collecting the evolved gas as it bubbles through an absorbing solution.
Reflux is the process of heating a substance in a liquid matrix to boiling to generate a vapor, continuously, condensing the vapor and returning the condensed vapor to the boiling liquid matrix. Refluxing is often necessary for chemical reactions that require elevated temperatures for long periods of time to reach completion. Refluxing allows prolonged heating of the sample without significant loss of original liquid matrix volume due to evaporation. Refluxed chemical reactions may also require the slow addition of a reagent during the reflux process to allow completion of specific chemical reactions.
Distillation and reflux processes have applications in both industrial-scale chemical production as well as bench-scale laboratory uses. With respect to bench-scale laboratory applications, standard procedures have developed for performing either the particular type of distillation necessary to remove the analyte of interest from the sample or the particular type of reflux necessary to chemically process the analyte of interest. For analytes such as cyanide, phenolic compounds, ammonia, hydrogen fluoride, volatile acids, sulfides and sulfites, to be removed from sample by distillation or chemically processed by refluxing, according to the standard procedures, a complicated, time-consuming distillation or reflux process is required which uses low-throughput, large volume, manual distillation or reflux apparatus including expensive, fragile, large glassware components that are not interchangeable between distillation or reflux methods.
The current state of the art is illustrated in FIGS. 1-5 which show prior art laboratory distillation and reflux apparatus. The prior art apparatus of FIGS. 1-5 disclose distillation and reflux glassware which is bulky and cumbersome due to the use of large boiling flasks. The large boiling flasks require correspondingly large glassware components which are expensive, fragile, and which require support apparatus such as rings, clamps, ring stands and lattice to support the glassware components above the boiling flasks. FIGS. 1-5 further illustrate that conventional large boiling flasks typically have one to three inlet necks for placing the sample and reagents in the flask and for attaching the other glassware pieces required to perform various distillations and refluxes, with the particular distillation or reflux method being performed dictating the type of multi-necked flask to be used. The different types of multi-necked boiling flasks each require specialized glassware components for connection only to that particular boiling flask such that glassware components are not interchangeable between distillation and reflux methods.
In use, the prior art distillation or reflux apparatus shown in FIGS. 1-5 typically require numerous hours for completion of the distillation or reflux process due to the lengthy assembly, disassembly and cleaning of the glassware. The large boiling flasks of prior art distillation or reflux apparatus typically require as much as 500 to 1000 mL of sample and such large sample sizes require correspondingly large volumes of costly reagent.
Each large boiling flask also requires a separate heating mantle, thereby consuming a lot of precious laboratory bench space. Since the boiling flasks often have irregular contact with the heating mantle, variable heating and generation of considerable waste heat during use often results. The heating mantles often become covered with reagent due to reagent spillovers onto the heating mantles causing the heating mantles to smoke during use. A support apparatus is required to hold the boiling flasks to the heating mantle while a second support apparatus is often required to support and distribute condenser water and gas or vacuum hoses to the distillation or reflux glassware with both supports requiring much lab space and set-up time.
U.S. Pat. No. 5,022,967 to Stieg discloses microdistillation apparatus which includes a plastic digestion tube within a micro-distillation column that is meant to be disposable after use. The apparatus uses a hydrophobic membrane in place of a conventional glass, cold water condenser and thus does not preserve the original distillation mechanism of the conventional glass, distillation glassware specified in standard distillation procedure. Further, the plastic fabrication of the micro-distillation column makes it unsuitable for use with organic solvents.
Thus, a need exists for laboratory distillation and reflux apparatus in which miniaturized glassware receptacles and components are used to perform distillations or refluxes of numerous smaller sample volumes, i.e., those in the 10 to 50 mL range, simultaneously at a single heat source.
A need also exists for laboratory distillation and reflux apparatus which includes glassware components that are interchangeable between distillation and reflux methods.
Still another need exists for laboratory distillation and reflux apparatus which includes glassware capable of being free-standing in the heating apparatus so as to eliminate the need for bulky support lattices and cumbersome heating mantles for each distillation or reflux which consumes precious laboratory space.
It would therefore be advantageous to scale down the glassware and heating arrangements of conventional distillation and reflux apparatus into a more compactly sized distillation and reflux system which allows numerous distillations and refluxes to take place simultaneously at a single heat source. The present invention provides an easily convertible mini-distillation and reflux system which includes scaled-down glassware pieces for connection to a boiling tube to be inserted into apertures of a heater block capable of holding glassware upright and freestanding in order to distill or reflux numerous samples simultaneously at a single heat source.
One advantage of the mini-distillation and reflux system of the present invention is that less laboratory bench space is required for distillations since numerous distillations can take place simultaneously within a compact space at a single heat source.
Another advantage of the mini-distillation and reflux system of the present invention is that the less bulky, miniaturized glassware is free-standing within a heater block to thus eliminate the need for support apparatus.
Still another advantage of the mini-distillation and reflux system of the present invention is that the assembly of both the miniaturized system and of the miniaturized glassware pieces is quicker and easier due to its smaller size. Thus, time and labor expenses, glassware breakage and replacement costs are all decreased.
Still another advantage of the mini-distillation and reflux system of the present invention is the use of a tubing distribution panel for delivery of condenser water and inert gases or vacuum to each glassware apparatus. The tubing distribution panel allows for quick, easy assembly of distillation and reflux equipment by eliminating bulky hose connectors and support lattice for hoses and tubing to decrease time and labor expenses.
Still another advantage of the mini-distillation system of the present invention is that less sample volume and reagents are required resulting in reduction in chemical and waste disposal costs.
Still another advantage of the mini-distillation and reflux system of the present invention is that a single heat source for multiple apparatus requires access to fewer electrical outlets and use of a low wattage single heat source results in decreased electrical operating costs.
The mini-distillation and reflux system of the present invention provides a distillation and reflux system that incorporates all of the advantages of a compactly sized system with interchangeable parts while allowing the scaled down interchangeable glassware to function in the same manner as the conventional glassware, thus preserving the chemical distillation and reflux mechanism of the original, conventional glassware specified in standardized distillation or reflux methods. The system further provides a major innovation by allowing a single inlet or one-necked boiling tube to replace the large volume, multi-necked boiling flasks of conventional distillation apparatus while functioning in the same manner as the one-, two-, or three-necked boiling flasks of the prior art.